The statement said "outstanding issues relating to Iran's nuclear program have yet to be resolved, and that the [International Atomic Energy] agency [IAEA] is not yet in a position to conclude that there are no undeclared nuclear materials or activities in Iran", AP said.

The IAEA asked its chief, Mohamed ElBaradei, to report on Iran's compliance by 3 September.

The resolution did not call for the case to be referred to the Security Council, which has the power to impose sanctions on Iran.

The IAEA's 35-member governing body met in emergency session for the past three days after Iran ended a nine-month suspension of work at Isfahan.

Iran insists it needs nuclear power as an alternative energy source, but Western nations fear it has plans to produce nuclear weapons.

The BBC's Emma Jane Kirby in Vienna, home to the IAEA's headquarters, says the US and Britain are calling for tough action against Iran.

Washington is calling for the UN to impose economic sanctions on Iran, on the grounds that Iran hid its uranium enrichment programme for 18 years.

But some countries fear a too heavy-handed approach could isolate it, as was the case with North Korea, and are finding it hard to agree, our correspondent says.